On Sun, 22 Jul 2001 11:26:45, Michael Witty <mw132 at mole.bio.cam.ac.uk>
wrote:
| Dear All,
| I plan to make a big column of PVPP to clean the phenolic
| compounds from a tobacco extract. If I want to save money on PVPP and
| more importantly personal effort making columns, how should I clean the
| column after use?
| Am I right to think that PVPP binds phenolics by hydrogen bonding?
| Should I disupt phenolic compound binding with methanol? or methanol
| plus 10% acetic acid?
|| Regards, Mike
Phenolics are thought to bind proteins via H-bonding to the carbonyl
oxygens of the peptide bond, so PVPP (a poly-alcohol) would be a protein
mimic that also binds phenolics.
I do not know what a "column" of PVPP might be -- PVPP ("high mol wt")
is a powder which, when you added a protein extract, would turn into a
gummy mess. One normally sequesters phenolics by adding PVPP to the
extraction buffer. And, because PVPP is dirt-cheap whereas phenolics are
nasty *#%$!, you want to mess with the PVPP-phenolic complex as little
as possible.
Another procedure which has worked for some in removing inhibitory
flavonoids and perhaps tannins, etc., is to run the extract over a gel
filtration column (Sephadex G-50 or equivalent).
More information on plant extracts can be found in Meth Enzymol 182,
174-193 (1990). There are more recent reviews which I don't have
indexed... there's also a lot of literature on the subject from plant
systematicists who assay isozymes, and plant biochemists/molecular
biologists who have to assay reporter genes in crude leaf extracts.
o----------------------------------------------------------------------o
| Dr. Peter Gegenheimer | Vox: 785-864-3939 FAX: 785-864-5321 |
| Department of | PGegen at KU.nospam.edu |
| Molecular Biosciences | http://rnaworld.bio.ukans.edu/ |
| University of Kansas |"When you have excluded the impossible, |
| 1200 Sunnyside Ave. | whatever remains, however improbable, |
| Lawrence KS 66045-7534 | must be the truth." S. Holmes |
o_____________________________|________________________________________o